1. Field
This disclosure relates to liquid crystal displays and other flat-panel matrix displays having an integral touch screen feature.
2. Description of the Related Art
Liquid crystal displays and other flat-panel matrix displays are widely used as flat panel televisions and as displays for desk-top and laptop computers. In some applications, a liquid crystal display panel and a touch screen sensor may be integrated to provide an apparatus that serves both as a display and an input device.
A typical touch screen sensor consists of two thin substrates separated by a small air gap. A transparent conductive film is deposited on one of the facing surfaces and a transparent resistive film is deposited on the second facing surface. The pressure of a finger or other object causes the two facing surfaces to touch. The location of the touch is determined by measuring the resistance, voltage, or current flow through several electrodes connected to the perimeter of the conductive film. Other touch screen sensors may use optical or acoustic technique to sense the touch location.
Touch screen sensors are usually separate devices that are attached to the front of the liquid crystal display panel. Separate touch screen sensors increase the cost and weight of the display unit. Additionally, touch screen sensors may degrade the clarity and contrast of the display panel.
Throughout this description, elements appearing in figures are assigned three-digit reference designators, where the most significant digit is the figure number and the two least significant digits are specific to the element. An element that is not described in conjunction with a figure may be presumed to have the same characteristics and function as a previously-described element having a reference designator with the same least significant digits.